Characteristics adjusting apparatus of physical quantity sensing device and a thermal type air flow measuring instrument, and associated adjusting method

ABSTRACT

The output characteristics of the sensing device or the control quantity of the sensing element can be adjusted by extracting an adjusting terminal in addition to a power source terminal, a ground terminal, an output terminal and the like outside a housing containing and protecting an electronic circuit. Further, by arranging the adjusting terminal inside a connector housing containing terminals such as the power source terminal, the ground terminal, the output terminal and the like, it is possible to prevent contact of foreign objects to the adjusting terminal and to water-proof the terminals for preventing corrosion since an associated connector is attached to the connector when the sensing device is actually used.

This application is a continuation on of application Ser. No.09/867,665, filed May 31, 2001, Ser. No. 09/524,763, filed Mar. 13,2000, and Ser. No. 08/900,517, filed Jul. 25, 1997.

BACKGROUND OF THE INVENTION

The present invention relates to a sensing device for detecting variouskinds of physical quantities, and more particularly to a sensing devicehaving a function for adjusting output characteristics of the sensingdevice or a control state of a sensing element.

A known way of adjusting output characteristics of an accelerationsensing device by applying an electric signal to an adjusting terminalis disclosed in Japanese Patent Application Laid-Open No. 5-340958. Theacceleration sensor has an acceleration detection processing circuitprovided with a sensitivity adjusting unit and a zero-point adjustingunit, and an adjusting unit capable of varying a basic outputcharacteristic of sensitivity. The adjusting unit is constructed of aplurality of resistors and switches, and on-off operation of the switchis performed by external on-chip trimming.

In the prior art described above, the adjusting terminals capable ofperforming on-off operation of the adjusting switches are provided on anelectronic circuit board, and in a fabrication process of the productthere are a filling process of a gel into a housing having the circuitboard inside after adjusting the output characteristic and heatingprocesses for bonding a cover and setting the gel and the coveradhesive. Variations of output characteristics in the final products arecaused by variations of output characteristics caused by the process.

Further, in an air flow measuring instrument for an internal combustionengine, in order to make it small in size, light in weight and low incost, it is preferable that an air flow sensing unit is integrated in ahousing containing a circuit board inside, and the housing is insertedand mounted so that the sensing device is positioned in an air intakeflow passage of the internal combustion engine. Since the adjusting workneeds to be performed by actually flowing air through the flow sensingunit, the air flow measuring instrument is mounted on a rigcorresponding to the air intake flow passage after almost completing thehousing and the flow sensing unit, and adjusting work is performed fromthe outside of the rig by actually flowing air. Apparatus capable ofperforming such adjusting work is necessary.

Particularly, in a thermal type air flow measuring instrument, thesensing element can be made small in size and the sensing element needsto be electrically connected to an electronic circuit for controllingthe sensing element and outputting. Therefore, it is possible to providea small-sized and low-cost air flow measuring instrument in which a flowsensing unit is integrated in a housing containing an electroniccircuit. However, since the electronic circuit is also placed in the airintake flow passage, adjusting work is performed from the outside of theair intake flow passage when the adjusting work is performed by actuallyflowing air through the flow sensing unit. Here again, apparatus capableof performing such adjusting work is necessary. Further, in a case wherethe sensing element is placed in an auxiliary passage from the viewpointof various kinds of performance and reliability, in taking it intoconsideration making the instrument small in size and low in cost, thenumber of parts is reduced by forming the auxiliary passage in thehousing and forming the auxiliary passage by the cover of the housing.However, in taking into consideration the effect of variations in shapesof the auxiliary passage on the output characteristics, it is necessaryto perform adjustment by actually flowing air after completion of theauxiliary passage, and apparatus capable of adjusting from external isfurther required.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a highly accuratesensing device, the characteristic adjustment of which can be performedin a final, i.e. the last, process step.

Another object of the present invention is to provide a low-cost sensingdevice in which the sensing elements and the electronic circuit areintegrated to reduce the number of parts, the size and the weight, andit is possible to easily perform the characteristic adjustment of thesensing device.

Another object of the present invention is to provide a sensing device,which is suitable for the environment of actual use, and in which thecharacteristic adjustment can be performed under a state that thesensing device is set in the environment of actual use.

In the present invention, for example, adjustment of outputcharacteristic can be performed in the final process in production ofthe devices as products, and occurrence of the variations of theproducts due to change in the output characteristic in such processes asfilling the gel and bonding the cover is suppressed.

In order to solve the above-mentioned problems and to achieve the aboveobjects, in addition to the electric power supply, ground and outputterminals which are provided in a common sensing device, an outputcharacteristic adjusting terminal of the sensing device or a controlquantity adjusting terminal of a sensing element is provided outside ahousing for containing an electronic circuit inside.

Further, in order to prevent problems such as corrosion of the terminalsor short-circuit caused by coming in contact with a conductive materialunder the environment of actual use of the sensing device, the adjustingterminal is covered with adhesive or the like, or the adjusting terminalis arranged inside a connector housing containing the electric powersupply, ground and output terminals so that foreign objects areprevented from coming in contacting with the terminals and the connectorhousing becomes a water-proof place under the environment of actual usein which the associating connector is connected. In that case, byarranging the adjusting terminal at a lower (deeper) level to the depthdirection of the connector housing than the level of the power sourceterminal etc., it is possible to prevent the power source terminal etc.from coming in contact with another thing, for example, contact with aprobe during adjusting work or contact with an associating connectorwhen the associating connector is connected. Further, by arranging theadjusting terminal in a hole provided on the bottom of the connectorhousing, it is possible to prevent electrical short-circuit duringadjusting work with more certainty.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional side view showing an embodiment of a sensingdevice in accordance with the present invention.

FIG. 2 is a view showing the sensing device being taken on the plane ofthe line II—II of FIG. 1.

FIG. 3 is an external view showing the sensing device seeing from thearrow III of FIG. 2.

FIG. 4 is a diagram showing the construction of an embodiment of acircuit in accordance with the present invention.

FIG. 5 is a diagram showing the construction of another embodiment of acircuit in accordance with the present invention.

FIG. 6 is a diagram showing the construction of a further embodiment ofa circuit in accordance with the present invention.

FIG. 7 is an external view showing another embodiment of a sensingdevice in accordance with the present invention viewed in the directionof the arrow III in FIG. 2.

FIG. 8 is a view showing the sensing device being taken on the plane ofthe line VIII—VIII of FIG. 7.

FIG. 9 is a cross-sectional side view showing a further embodiment inaccordance with the present invention.

FIG. 10 is a cross-sectional side view showing the sensing device ofFIG. 9.

FIG. 11 is an external view showing the sensing device viewed in thedirection of the arrow XI of FIG. 10.

FIG. 12 is a view showing an embodiment of a control system in which thepresent invention is used.

DESCRIPTION OF PREFERRED EMBODIMENTS

In the present invention, thermal type air flow measuring instrumentsare shown as typical embodiments. Since the other kinds of physicalquantity sensing devices are basically the same as the thermal type airflow measuring instrument only except for their particular sensingelement and arranging method, a description of other types ofembodiments will be omitted.

Referring first to FIGS. 1-3, an electronic circuit 4 is bonded andfixed onto a metallic base 6, and surrounded by a housing 5 which isalso bonded and fixed to the metallic base 6 or insert-formed in a unitwith the metallic base 6.

The housing 5 is a plastic part which is insert-formed with metallicparts of connector terminals 2, adjusting terminals 1 and sensingelement terminals 9 (the metallic base 6 may be also insert-formed, asdescribed above). In addition to a function to contain and protect anelectronic circuit 4, the housing 5 is integrated in a unit togetherwith an auxiliary passage 13, a connector housing 3, a fixing flange 10,etc. Therefore, the electronic circuit 4 is contained in a box-shapedbody composed of the metallic base 6 as the bottom and the housing 5 asside walls. The adjusting terminals 1 and the connector terminals 2penetrate from the inner side of the box-shaped body containing theelectronic circuit 4 to the inside portion of the connector housing 3.By connecting the terminal near an inner side end of the housing 5 andthe electronic circuit 4 with metallic wires 8, the electronic circuit4, the adjusting terminals 1 and the connector terminals 2 inside theconnector housing 3 are electrically connected. Similarly, the sensingterminals 9 penetrate from the inner side of the box-shaped bodycontaining the electronic circuit 4 to the auxiliary passage 13. Byconnecting the terminals near the other end of the inner side of thehousing 5 and the electronic circuit 4 with metallic wires 8, and bywelding a heating resistor 11 and a temperature compensating resistor 12to the sensing terminals 9 in a side end portion of the auxiliarypassage 13, the heating resistor 11 and the temperature compensatingresistor 12 are brought in electrical continuity with the electroniccircuit 4. Then, the interior of the box-shaped body containing theelectronic circuit 4 is filled with a silicon gel 19, and the electroniccircuit 4 is sealed by bonding a cover 7 (actually, the box-shaped bodyis opened only through a ventilation hole 18 for leaking air remaininginside the housing 5 to the inner side of the connector housing 3 whenthe air is heated and expanded). The terminals except for the connectorterminal 2, the adjusting terminals 1 and the sensing element terminals9 are electrically insulated. Further, by bonding the cover 7, theauxiliary passage 13 is completed as a passage having an openingupstream of the housing 5 as an inlet 13 a and a square hole bored inthe housing 5 and the cover 7 as an outlet 13 b. The reason why theauxiliary passage 13 is formed in such a complex-shaped passage having abend as shown in this embodiment is that the structure is effective inpreventing the sensing elements from fouling, suppressing air flowdisturbance and reducing sensing error due to pulsating flow, andtherefore the structure is suitable for intake air sensing of aninternal combustion engine. This module is inserted through a hole in anouter wall surface of a body 14 and attached so that the inlet 13 a andthe outlet 13 b of the auxiliary passage 13 are positioned inside themain passage 15, and a fixing flange 10 integrally formed in the housing5 is fixed onto the body 14 using screws 16. Thus, the structure of thethermal type air flow measuring instrument is completed.

By employing this structure, it is possible to reduce the number ofparts and largely reduce the cost. Further, even though the auxiliarypassage employs such a complex structure as to have the bend, thehousing 5 can be formed easily through plastic forming, and can be verysmall in size, light in weight, small in the number of parts and lowcost. Furthermore, the thermal type air flow measuring instrument can beinserted and mounted to an existing component of an air intake systemsuch as an air cleaner without setting such a body described above.

Measured air flow rate is the total flow rate of air flowing in the mainpassage 15 in the body 14 in the main flow direction. The total flowrate is detected based on an amount of heat radiated from the heatingresistor 11 arranged inside the auxiliary passage 13 into which part ofair flowing in the main passage flows. Therefore, since the measuringaccuracy is affected by variations existing among the products such asvariations in structures of the heating resistor 11, in shapes of thepassage, in elements of the electronic circuit and so on, it isnecessary to individually adjust output characteristics of the products.

In an embodiment where the adjusting terminals are arranged on theelectronic circuit or the characteristic adjustment is performed bylaser trimming of a resistor or the like as in the prior art, it isimpossible to perform the adjustment after completion of the structureof a thermal type air flow measuring instrument as in the presentinvention. Accordingly, the adjustment cannot be performed in a statewhere the electronic circuit 4 is exposed at a time before the cover 7is bonded. Therefore, since the processes of filling of the silicon gel19, bonding of the cover and thermo-setting to the box-shaped body ofthe housing 5 containing the electronic circuit 4 are required afterperforming adjustment, changes in characteristic due to these processesare a factor to cause variations among the products and degrade them.However, in the present invention, since characteristic adjustment canbe performed by applying electric signals to the adjusting terminals 1provided inside the connector housing after completion of the structure,the adjusting work can be performed in the final process andconsequently characteristic changes after adjusting can be eliminated.Further, since shipping inspection may be eliminated or shippinginspection may be performed in the adjusting process, the inspectionprocess can be easily performed.

Furthermore, in the thermal type air flow measuring instrument, thecharacteristic adjustment needs to be performed by actually flowing air.Particularly, in this embodiment, it is preferable that thecharacteristic adjustment is performed with the final construction ofthe product by flowing air to the main passage 15 under a state in whichit is attached to the body 14. Therefore, in the conventionaltechnology, the structure having the electronic circuit 4 inside thebody 14 has been very difficult to adjust by flowing air through themain passage 15. However, according to the present invention, adjustmentcan be easily performed using the adjusting terminal 1 inside theconnector housing 3 arranged outside the body 14, as described above.Further, in the thermal type air flow measuring instrument, in orderthat an air flow rate can be measured based on an amount of heatradiated from the heating resistor to the air, the heating resistor 11is heating-controlled by the electronic circuit 4 so as to keep aconstant temperature difference to the temperature compensating resistor12. Since variations in the amounts of heats among the products occur,adjustment of the electronic circuit 4 is also required. In the presentinvention, it is also possible to adjust such a control quantity of thesensing element easily, as described above.

In an actual adjusting process, the connector terminal 2 and a lineadjusting apparatus need to be electrically connected in order to drivethe thermal type air flow measuring instrument to measure its output,and the adjusting terminal 1 and the line adjusting apparatus need to beelectrically connected in order to apply an electric signal to theadjusting terminal 1. Since these connections are temporary for onlyadjusting work, the adjusting work is usually performed by pressingprobes provided in the line adjusting apparatus pressed to theindividual terminals. In this embodiment, since all the terminals arearranged inside the connector housing 3, the connection is easilyperformed by pressing all the probes in the same direction. However, onthe contrary, since there are many terminals in a narrow space,erroneous contact between the terminals and the probes may be caused.Therefore, the adjusting terminal 1 is arranged in a deeper portion ofthe connector housing 3 so that the power source probe may not reach theadjusting terminal 1. In addition, the adjusting terminal 1 is arrangedin a hole formed on the bottom surface of the connector housing 3 sothat only the probe having a top front diameter smaller than that of thehole can be connected to the adjusting terminal 1. Further, byinsulating the outer periphery of the probe for the adjusting terminal,it is possible to eliminate electric short-circuiting caused by contactwith the connector terminal 2 or the other probes.

In practical use of the thermal type air flow measuring instrument, theinside of the connector housing is usually water-proofed by connectingan associated connector to the connector terminal 2 and also connectingan associated connector to the connector housing 3. Thereby, problems ofcorrosion of the adjusting terminal 1 and electrical short-circuitingwith the other terminals are prevented.

The construction of the electronic circuit in accordance with thepresent invention will be described below, referring to FIG. 4 to FIG.6.

In the embodiment shown in FIG. 4, a transmitting system is switched byan electric signal applied to an adjusting terminal 100 using amultiplexer 105 to perform adjustment of an output characteristic andsensing element control quantity using an output characteristicadjusting circuit 104 and a control quantity adjusting circuit 102.

The electronic circuit 4 can be roughly classified into a controlcircuit 101, an output processing circuit 103 and the multiplexer 105.The control circuit 101 is electrically connected to the heatingresistor 11 and the temperature compensating resistor 12 arranged in theauxiliary passage 13. Further, the control circuit 101 has the controlquantity adjusting circuit 102. The output processing circuit 103 is acircuit for converting an electric signal obtained from the controlcircuit 101 into a predetermined output signal, and has the outputcharacteristic adjusting circuit 104. The power source terminal 106, theoutput terminal 107 and the ground terminal 108 are arranged in theconnector housing 3 and connected to external units.

Different from that of FIG. 4, the embodiment of FIG. 5 has nomultiplexer, but can adjust only output characteristic from the outsideof the electronic circuit 4.

The electronic circuit 4 can be roughly classified into a controlcircuit 101 and an output processing circuit 103, and the outputprocessing circuit has a output characteristic adjusting circuit 104.The output characteristic adjusting circuit 104 is a circuit capable ofadjusting output characteristic by switching on-off, and the switchingon-off can be performed by applying an electric signal to the adjustingterminal 100. The adjusting terminal 100 is extended outside theelectronic circuit 4 so that the electric signal can be applied from theoutside of the housing containing and protecting the electronic circuit4.

In the embodiment of FIG. 6, output processing is performed by amicrocomputer (CPU) 111. The electronic circuit 4 can be roughlyclassified into a control circuit 101, an A/D converter 110, the CPU111, a memory 112 and an interface 113. The control circuit 101 iselectrically connected to a heating resistor 11 and a temperaturecompensating resistor 12 as in the embodiments of FIG. 4 and FIG. 5, andthe control may be employ not only analog control but digital control aswell. The A/D converter 110 converts an electric signal of the controlcircuit 101 into a digital signal. The CPU 111 performs calculation byprocessing the digital signal based on data stored in the memory 112 toconvert the digital signal into an appropriate signal, and the outputsignal is output as a signal matching an external unit receiving thesignal using the interface circuit 113.

Therefore, in this embodiment, the characteristic adjustment can beperformed by storing optimized values in the memory.

When resolution of output characteristic adjustment is increased in thecircuit construction described in FIG. 5, the number of adjustingterminals is increased. Therefore, it becomes difficult from theviewpoint of space to arrange all the adjusting terminals inside theconnector housing as in the embodiments explained by FIG. 1 to FIG. 3.

Therefore, description will be made below on an embodiment where theadjusting terminals are arranged outside a connector housing, referringto FIG. 7 and FIG. 8. Since the construction of the thermal type airflow measuring instrument is the same as the embodiments of FIG. 1 andFIG. 2, description of the instrument will be omitted here.

Connector terminals 2 are arranged inside a connector housing 3 shown inFIG. 7, and adjusting terminals 1 are aligned and arranged in adepressed portion 21 on the upper surface of a fixing flange 10.Therefore, in this embodiment, the characteristic adjustment can beperformed after completion of the construction of the thermal type airflow measuring instrument by applying electric signals to the adjustingterminals 1. In an embodiment where the adjusting terminals are arrangedin the connector housing, the adjusting terminals 1 are water-proofedand avoid contact with the other parts by attaching the associatedconnector when it is used in practice. However, since the adjustingterminals 1 are arranged outside the connector housing 3 in thisembodiment, the adjusting terminals 1 are exposed even when theassociated connector is attached. Therefore, by filling the depressedportion 21 with an adhesive 20 to coat the adjusting terminals 1, theadjusting terminals 1 are water-proofed and avoid contact with the otherparts. Instead of using the adhesive 20, a method in which the adjustingterminals are covered with another member can be employed, or a methodin which the adjusting terminals are coated with an insulator.

Description will be made below on an embodiment where a sensing deviceis set in a portion of which the surrounding is closed, referring toFIG. 9 to FIG. 11.

The thermal type air flow measuring instrument 210 is inserted into aninner duct 31 integrated with an air cleaner clean side housing 27 in aunit so that an inlet 13 a and an outlet 13 b of an auxiliary passage 13is positioned in the inner portion of the inner duct 31. An air filter29 is fixed between the air cleaner clean side housing 27, and an aircleaner dirty side housing 26. An inlet duct 25 is attached in the aircleaner dirty side housing 26, and a connecting duct 30 is attacheddownstream of the inner duct 31 of the air cleaner clean side housing27. An internal combustion engine is arranged downstream of theconnecting duct 30. Therefore, flow of intake air shown by main flowdirection 17 flows into the air cleaner dirty side housing 26 from theinlet duct 25, and then into the inner duct 31 from the air cleanerclean side housing 27 passing through the air filter 29. Here, the innerduct 31 corresponds to the main passage 15 of the thermal type air flowmeasuring instrument 210, and part of the air lowing through the mainpassage 15 flows into the auxiliary passage 13 and then into theinternal combustion engine through the connecting duct 30.

In the thermal type air flow measuring instrument 210 shown in FIG. 10,a holder 32 holding a sensing element terminal 9 is integrated with ametallic base 6 in a unit. An auxiliary passage structural member 33 isarranged so that a heating resistor 11 and a temperature compensatingresistor 12 are positioned inside the auxiliary passage 13. Anelectronic circuit 4 is fixed on the upper surface of the metallic base6, and a housing 5 is also fixed on the upper surface of the metallicbase 6 so as to contain the electronic circuit 4. The electronic circuit4, the sensing element terminal 8 and a lead frame 34 are electricallyconnected with a metallic wire 8. The lead frame 34 is extended outsidethe housing 5 to be connected to a wire-harness 22, and a connector 24is arranged in the opposite end portion of the wire-harness 22. Theconnector 24 is composed of a connector housing 3 containing connectorterminals 2 and adjusting terminals 1. The connector terminals 2 and theadjusting terminals 1 are electrically connected to the electroniccircuit 4 through the wire-harness 22, the lead frame 34 and themetallic wires 8. Therefore, as in the above-mentioned embodiment, thecharacteristic adjustment can be performed by applying an electricsignal to the adjusting terminal 1 after fixing the cover 7 onto thehousing 5 and the electronic circuit 4 is completely covered.

Further, in this embodiment, although the thermal type air flowmeasuring instrument 210 is fixed to the inner duct 31 and placed in theair cleaner 200 having the air filter 29 and the air cleaner dirty sidehousing 26, the connector 24 is led out in the outside of the aircleaner 200. A connector extracting hole 35 of the air cleaner cleanside housing 27 seen in FIG. 9 is sealed by a rubber boot 23 provided inthe middle of the wire-harness 22. Therefore, according to thisembodiment, even after the sensing device, i.e., the thermal type airflow measuring instrument 210, is set in an enclosed place of actualuse, that is, the inside of the air cleaner 200, the characteristicadjustment can be performed by applying an electric signal to theadjusting terminal 1 of the connector 24 which has been led outside.Further, the characteristic adjustment can be performed under a state ofactual use, that is, after it is installed in the air cleaner 200.

Finally, description will be made below on an embodiment of an internalcombustion engine of electronic control fuel injection type which athermal type air flow measuring instrument in accordance with thepresent invention is applied to, referring to FIG. 12.

Intake air 201 entering from an air cleaner 200 is sucked into an enginecylinder 207 though a body 202 of a thermal type air flow measuringinstrument, a duct 203 and an intake manifold 206 having a throttle body204 and an injector 205 for fuel supply. Exhaust gas 208 produced in theengine cylinder 207 is exhausted through an exhaust manifold 209.

An air flow signal output from an electronic circuit of the thermal typeair flow measuring instrument 210, a throttle valve opening signaloutput from a throttle angle sensor 211, an oxygen concentration signaloutput from an oxygen sensor 212 provided in the exhaust manifold 209and a rotating speed signal output from an engine rotating speed sensor213 are input to a control unit 214. The control unit 214 outputssignals such as an idle control valve opening, etc. under an optimumfuel injection rate obtained by calculation processing to control theinjector 205 and the idle air control valve 215.

According to the present invention, a highly accurate sensing device canbe provided since the characteristic adjustment of the sensing devicecan be performed in a final process, and accordingly it is possible toprevent a change in the characteristics produced in the processes afterthe adjustment such as gel filling, cover bonding, thermo-fittingprocesses in the conventional sensing device. Further, a low-costsensing device can be provided since the sensing elements and theelectronic circuit are integrated to reduce number of the parts, thesize and the weight. Also, it is possible to easily perform thecharacteristic adjustment of the sensing device. Furthermore, a sensingdevice suitable for the environment of actual use can be provided sincethe characteristic adjustment can be performed under a state that thesensing device is set in the environment of actual use.

Although the invention has been described and illustrated in detail, itis to be clearly understood that the same is by way of illustration andexample, and is not to be taken by way of limitation. The spirit andscope of the present invention are to be limited only by the terms ofthe appended claims.

What is claimed is:
 1. A characteristic adjusting means of a physicalquantity sensing device having a sensing element for detecting variousphysical quantities and an electronic circuit electrically connected tosaid sensing element for processing a controlled or a detected quantityof said sensing element as an electric signal, comprising: an adjustingcircuit provided in said electronic circuit for performing adjustment ofoutput characteristic or adjustment of a controlled quantity or detectedquantity of the sensing element; a housing for containing saidelectronic circuit inside; and an adjusting terminal, electricallyconnected to said adjusting circuit and provided outside said housing;wherein the output characteristic or the controlled quantity is madepossible to be adjusted by applying an electric signal to said adjustingterminal.
 2. A characteristic adjusting means of a physical quantitysensing device according to claim 1, wherein said adjusting terminal iselectrically insulated from external by covering with another materialor an adhesive after the adjustment.
 3. A characteristic adjusting meansof a physical quantity sensing device according to claim 1, wherein saidadjusting terminal is arranged outside and near a connector housingcontaining therein connector terminals for an output terminal fortransmitting an output signal of said electronic circuit to externalequipment, a power source terminal for connecting to an power source ora common ground, a ground terminal and so on.
 4. A characteristicadjusting means of a physical quantity sensing device according to claim1, wherein said adjusting terminal is arranged inside a connectorhousing containing therein connector terminals for an output terminalfor transmitting an output signal of said electronic circuit to externalequipment, a power source terminal for connecting to an power source ora common ground, a ground terminal and so on.
 5. A characteristicadjusting means of a physical quantity sensing device according to claim4, wherein said adjusting terminal is placed at a farther (deeper)position from an opening end of said connector housing than saidconnector terminal.
 6. A characteristic adjusting means of a physicalquantity sensing device according to claim 5, wherein said adjustingterminal is placed in a hole provided on the bottom of said connectorhousing.
 7. A characteristic adjusting means of a physical quantitysensing device according to claim 4, wherein said connector housingbecomes a water-proof structure for proofing the inside portion of theconnector housing when the associating connector is connected.
 8. Acharacteristic adjusting means of a physical quantity sensing deviceaccording to claim 3, wherein said housing is formed in a one-piecestructure together with the housing of said electronic circuit byembedding said connector terminal and said adjusting terminal.
 9. Acharacteristic adjusting means of a physical quantity sensing deviceaccording to claim 1, wherein a multi-plexer is provided between saidadjusting circuit and said adjusting terminal.
 10. A characteristicadjusting means of a physical quantity sensing device according to claim1, wherein the output characteristic or the controlled quantity is madepossible to be adjusted by applying an electric signal to said adjustingterminal after installing said electronic circuit inside said housing.11. A physical quantity sensing device comprising the characteristicadjusting means according to claim
 1. 12. An air flow measuringinstrument comprising the characteristic adjusting means according toclaim
 1. 13. A thermal type air flow measuring instrument for detectingan intake air flow rate of an internal combustion engine comprising thecharacteristic adjusting means according to claim
 1. 14. A thermal typeair flow measuring instrument comprising at least one heating resistorarranged in an auxiliary passage through which part of air flowingthrough an air intake passage of an internal combustion engine flows;and an electronic circuit for controlling heating temperature of saidheating resistor and for outputting a signal corresponding to a flowrate of air flowing through the air intake passage based on a quantityof heat radiated from the heating resistor to the air, which comprisesan output characteristic adjusting circuit for adjusting outputcharacteristic or a control adjusting circuit for adjusting a heatingstate of said heating resistor provided in said electronic circuit and ahousing containing therein said electronic circuit, and which furthercomprises, outside said housing, an adjusting terminal electricallyconnected to said adjusting circuit for transmitting an electric signalto said adjusting circuit; and at least one of: an output terminalconnecting said electronic circuit and external devices for transmittingan output signal of said electronic circuit, a power source terminalconnected to an power source, and a ground terminal electricallyconnected to the ground; and wherein said adjusting terminal and saidconnector terminal are positioned outside the air intake passage whensaid housing its inserted through and fixed to a hole provided on thewall surface of said air intake passage so that said auxiliary passageis positioned in the air intake passage.
 15. A thermal type air flowmeasuring instrument according to claim 14, wherein said adjustingterminal is electrically insulated from outside by covering with anothermaterial or an adhesive after the adjustment.
 16. A thermal type airflow measuring instrument according to claim 14, wherein said connectorterminal and said adjusting terminal are contained in a connectorhousing which is integrated with the housing containing therein saidelectronic circuit.
 17. A thermal type air flow measuring instrumentaccording to claim 14, wherein said connector terminal and saidadjusting terminal are contained in a connector housing separated fromsaid housing, and said connector housing and said housing are connectedwith a sheathed lead wire.
 18. A thermal type air flow measuringinstrument according to any one of claim 16, wherein said adjustingterminal is placed at a farther or deeper position from an opening endof said connector housing than said connector terminal.
 19. A thermaltype air flow measuring instrument according to claim 17, wherein saidadjusting terminal is placed at a farther or deeper position from anopening end of said connector housing than said connector terminal. 20.A thermal type air flow measuring instrument according to claim 18,wherein said adjusting terminal is placed in a hole provided on thebottom of said connector housing.